Active photonics based on phase-change materials and reconfigurable nanowire systems

Metamaterials that derive their properties from the subwavelength structure of meta-atoms offer unprecedented flexibility for manipulating light-matter interaction. To promote the development of practical metadevices, considerable efforts have been made to achieve photonic metamaterials that exhibit an active response under external stimuli. The primary strategy is to incorporate active materials that possess variable refractive index into the design of metamaterials. Among the various active materials, phase-change materials have recently attracted particular attention due to their variation of material properties in a broad frequency band. On the other hand, as structures and geometric arrangement of building blocks (i.e., artificial atoms or meta-atoms) determine the properties of metamaterials, reconfigurable metamaterials based on mechanical tuning have also been intensively studied. Unlike most reported mechanically tunable metamaterials based on elastic and electromagnetic forces, directed self-assembly (DSA) of nanoparticles opens a new path for low-cost, large-area reconfigurable photonic systems. In this chapter, we present our findings on active photonics metadevices based on phase transition of vanadium dioxide (VO2) and reconfigurable nanowire assemblies. Our work shows the potential of the proposed metamaterial systems for applications ranging from electro-optical information process, storage, and display to energy-efficient smart windows.